arXiv subjects

Yinchieh Lai

Publications and source records attributed to Yinchieh Lai.

9 recordsLinked to original sources

arXiv2005

Photon-number fluctuation and correlation of bound soliton pairs in mode-locked fiber lasers

Quantum photon-number fluctuation and correlation of bound soliton pairs in mode-locked fiber lasers are studied based on the complex Ginzburg-Landau equation model. We find that, depending on their phase difference, the total photon-number noise of the bound soliton pair can be larger or smaller than that of a single soliton and the two solitons in the soliton pairs are with positive or negative photon-number correlation, correspondingly. It is predicted for the first time that out-of-phase soliton pairs can exhibit less noises due to negative correlation.

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arXiv2004

Quantum correlations in the soliton collisions

We study quantum correlations and quantum noise in the soliton collision described by a general two-soliton solution of the nonlinear Schrödinger equation, by using the back-propagation method. Our results include the standard case of a $sech$-shaped initial pulse analyzed earlier. We reveal that double-hump initial pulses can get more squeezed, and the squeezing ratio enhancement is due to the long collision period in which the pulses are more stationary. These results offer promising possibilities of using higher-order solitons to generate strongly squeezed states for the quantum information process and quantum computation.

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arXiv2004

Squeezing and entanglement of matter-wave gap solitons

We study quantum squeezing and entanglement of gap solitons in a Bose-Einstein condensate loaded into a one-dimensional optical lattice. By employing a linearized quantum theory we find that quantum noise squeezing of gap solitons, produced during their evolution, is enhanced compared with the atomic solitons in a lattice-free case due to intra-soliton structure of quantum correlations induced by the Bragg scattering in the periodic potential. We also show that nonlinear interaction of gap solitons in dynamically stable bound states can produce strong soliton entanglement.

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arXiv2004

Quantum correlations in bound-soliton pairs and trains in fiber lasers

Quantum correlations in pairs and arrays (trains) of bound solitons modeled by the complex Ginzburg-Landau equation (CGLE) are calculated numerically, on the basis of linearized equations for quantum fluctuations. We find strong correlations between the bound solitons, even though the system is dissipative. Some degree of the correlation between the photon-number fluctuations of stable bound soliton pairs and trains is attained and saturates after passing a certain distance. The saturation of the photon-number correlations is explained by the action of non- conservative terms in the CGLE. Photon-number-correlated bound soliton trains offer novel possibilities to produce multipartite entangled sources for quantum communication and computation.

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arXiv2004

Quantum Fluctuations around Bistable Solitons in the Cubic-Quintic nonlinear Schrödinger equation

Small quantum fluctuations in solitons described by the cubic-quintic nonlinear Schrödinger equation (CQNLSE) are studied with the linear approximation. The cases of both self-defocusing and self-focusing quintic term are considered (in the latter case, solitons may be effectively stable, despite the possibility of collapse). The numerically implemented back-propagation method is used to calculate the optimal squeezing ratio for the quantum fluctuations vs. the propagation distance. In the case of the self-defocusing quintic nonlinearity, opposite signs in front of the cubic and quintic terms make the fluctuations around bistable pairs of solitons (which have different energies for the same width) totally different. The fluctuations around nonstationary Gaussian pulses in the CQNLSE model are studied too.

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arXiv2004

Quantum Theory of Fiber Bragg Grating Solitons

Following the pioneering work of Prof. Hermann A. Haus, a general quantum theory for bi-directional nonlinear optical pulse propagation problems is developed and applied to study the quantum properties of fiber Bragg grating solitons. Fiber Bragg grating solitons are found to be automatically amplitude squeezed after passing through the grating and the squeezing ratio saturates after a certain grating length. The optimal squeezing ratio occurs when the pulse energy is slightly above the fundamental soliton energy. One can also compress the soliton pulsewidth and enhance the squeezing simultaneously by using an apodized grating, as long as the solitons evolve adiabatically.

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arXiv2003

Fluorescence Spectra of a Two-Level Atom Embedded in a Three-Dimensional Photonic Crystal

Steady-state fluorescence spectra of a two-level atom embedded in a three-dimensional photonic bandgap crystal and driven by a monochromatic classical electrical field is calculated theoretically for the first time as we know. The non-Markovian noises caused by the non-uniform distribution of photon density of states near the photonic bandgap are handled by a new approach in which the Liouville operator expansion is utilized to linearize the generalized optical Bloch equations. The fluorescence spectra are then directly solved by the linearized Bloch equations in the frequency domain. We find that if the atomic energy level is far from the bandgap, fluorescence spectra with Mollow's triplets are observed. However, when the atomic energy level is near the bandgap, the relative magnitude and the number of the fluorescence peaks are found to be varied according to the wavelength offset.

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arXiv2003

Resonance Fluorescence Squeezing Spectra from Photonic Bandgap Crystals

The fluorescence intensity and quadrature spectra from a two-level atom embedded in a photonic bandgap crystal and resonantly driven by a classical pump light are calculated. The non-Markovian nature of the problem caused by the non-uniform distribution of the photonic density of states is handled by linearizing the generalized optical Bloch equations with the Liouville operator expansion. Unlike the case in free space, we find that the bandgap effects will not only modify the fluorescence spectral shape but also cause squeezing in the in-phase quadrature spectra.

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arXiv2003

Amplitude squeezed fiber Bragg grating solitons

Quantum fluctuations of optical fiber Bragg grating solitons are investigated numerically by the back-propagation method. It is found for the first time that the bandgap effects of the grating act as a nonlinear filter and cause the soliton to be amplitude squeezed. The squeezing ratio saturates after a certain grating length and the fundamental Bragg soliton produces the optimal squeezing ratio.

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